High-hardness injection-molded tungsten carbide particle reinforced iron-based alloy and preparation method thereof

Abstract

The invention provides a high-toughness injection molding copper-based alloy. The high-toughness injection molding copper-based alloy comprises the following components in parts by weight: 80-85 parts of Cu; 3 to 5 parts of Cu-coated Al-coated Ti-B composite powder; 4 to 5.5 parts of Ni; 2.5 to 3.5 parts of Sn; 0.8 to 1.2 parts of Zr; and 0.15 part of La / Ce rare earth with the mixing ratio of 1: 1. The Cu-Al-Ti-B core-shell composite powder is introduced, a triple mechanism of nanophase in-situ toughening / grain boundary strengthening / rare earth purification is constructed, and the problem that a conventional MIM copper-based alloy is insufficient in toughness is thoroughly solved.

Description

Technical Field

[0001] This invention relates to the field of metal alloys, specifically to a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy and its preparation method. Background Technology

[0002] In fields such as machinery manufacturing, mining, and oil drilling, a large number of components must withstand high loads, severe wear, and complex working conditions, placing stringent requirements on the hardness, wear resistance, and mechanical properties of materials. While traditional iron-based alloys possess good toughness and machinability, their insufficient hardness and wear resistance make them unsuitable for use under extreme conditions. On the other hand, single-material cemented carbides (such as tungsten carbide-based alloys) suffer from poor toughness, difficulty in forming, and high manufacturing costs, limiting their application in complex-shaped components. Injection molding, as a near-net-shape forming process, enables the efficient and high-precision fabrication of complex-shaped parts, effectively reducing subsequent processing costs. Based on this, this paper proposes a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy. By introducing high-hardness tungsten carbide particles as a reinforcing phase into an iron-based matrix, and combining the advantages of injection molding, a composite alloy material with high hardness, good wear resistance, and a certain degree of toughness is prepared. This addresses the application bottleneck of traditional materials under extreme wear conditions and meets the urgent needs of various industries for high-performance wear-resistant parts. Summary of the Invention

[0003] Technical problem to be solved: The purpose of this invention is to provide a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy. Tungsten carbide (WC) particles are selected as the reinforcing phase, and the hardness and wear resistance of the alloy are significantly improved through the synergistic effect of Cr, Ni, Mo and other elements, making it suitable for high wear conditions.

[0004] Technical solution: A high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy, wherein the iron-based alloy comprises the following components by weight percentage: The composition of the material is as follows: WC 4.5~5.5wt%, C 0.4~0.5wt%, Cr 1.2~1.5wt%, Ni 0.9~1.1wt%, Mo 0.3~0.45wt%, Si 0.3~0.6wt%, Mn 0.5~0.8wt%, nano-Al2O3@Co-Y2O3 composite modified particles 0.8~1.5wt%, and the remainder is Fe; In WC, fine particles of 1-5μm account for 60-70 wt%, and coarse particles of 5-10μm account for 30-40 wt%.

[0005] Preferably, the preparation method of the nano-Al2O3@Co-Y2O3 composite modified particles includes the following steps: S11. Add aluminum isopropoxide to isopropanol at a mass ratio of 5:3, stir and reflux, then add dilute nitric acid at a molar ratio of 1:0.05 to obtain a sol, let it stand for aging, dry it, and grind it to obtain a white powder. S12. Place the white powder in a muffle furnace, heat it to 550~600℃, and maintain it for 2~3 hours to obtain porous Al2O3 powder; S13. Add porous Al2O3 powder to a mixed solution of cobalt nitrate and yttrium nitrate. The concentration of cobalt nitrate is 0.4~0.8 mol / L, and the concentration of yttrium nitrate is 0.2~0.3 mol / L. The mass-volume ratio of porous Al2O3 powder to the mixed solution is 1 g: 20~30 mL. Stir for 2~4 h, let stand for 10~15 h, filter and dry, and finally calcine to obtain Al2O3@Co-Y2O3 composite modified particles. Then grind to obtain nano-Al2O3@Co-Y2O3 composite modified particles of 300~800 nm.

[0006] The above-mentioned method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloys includes the following steps: S1. The metal elements in the weighed iron-based alloy powder are melted and atomized to obtain alloy particles. The alloy particles, C, WC and nano Al2O3@Co-Y2O3 composite modified particles are added to a mixer for mixing to obtain a premix. S2. Add the premix and binder to the mixer. The binder is paraffin wax, polyethylene, polypropylene and stearic acid mixed in a mass ratio of 60~70:20~25:5~10:2~5 to obtain the mixture. S3. Inject the mixture into the mold, perform injection molding, and then degrease with n-heptane. After solvent degreasing, perform microwave-assisted thermal degreasing. S4. The degreased green blank is sintered and post-treated to obtain a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy.

[0007] Preferably, the ratio of premix to binder in S2 is 100:5~9.

[0008] Preferably, the process parameters for microwave-assisted thermal degreasing in S3 are as follows: Stepwise heating degreasing is adopted: the room temperature is heated to 100°C at a heating rate of 5°C / min, then heated to 200°C at a heating rate of 8°C / min, and held for 0.5h. Then, the temperature is heated to 300°C at a heating rate of 8°C / min, and held for 1h. Then, the temperature is heated to 450°C at a heating rate of 8°C / min, and held for 1h. Finally, the temperature is heated to 600°C at a heating rate of 5°C / min, and held for 0.5h.

[0009] Preferably, the sintering process parameters in S4 are as follows: heating from room temperature to 800°C at a heating rate of 5°C / min, heating from 800°C to 1200°C at a heating rate of 3°C / min, and heating from 1200°C to 1380~1420°C at a heating rate of 2°C / min.

[0010] Preferably, the post-treatment process in S4 is as follows: the alloy is cooled in the furnace to 860~880℃, held for 10~15min, then transferred to a salt bath at 200~220℃ for graded cooling for 5~8min, cooled to -196℃ at a rate of 5℃ / min, held for 2~3h for cryogenic treatment, and then heated in the furnace to 180~200℃, held for 2~3h, and air-cooled to room temperature.

[0011] Beneficial effects: The high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy of the present invention has the following advantages: In this invention, 4.5~5.5wt% WC particles are used as the reinforcing phase, combined with an optimized gradation design of 1-5μm fine particles (60~70wt%) and 5-10μm coarse particles (30~40wt%). The fine particles can fill the gaps between the coarse particles to increase the density, while the coarse particles provide structural support to avoid stress concentration. Combined with the second-phase reinforcing effect of nano-Al2O3@Co-Y2O3 composite modified particles, the hardness of the alloy is significantly improved, and the wear resistance is greatly improved compared with traditional iron-based alloys, which can meet the requirements of high wear conditions. In this invention, nano-Al2O3@Co-Y2O3 composite modified particles are used. The porous Al2O3 carrier prepared by a specific process provides a stable dispersion substrate for Co and Y2O3. Co can reduce the interfacial energy between WC and the iron matrix and promote interfacial compatibility. Y2O3 inhibits the formation of brittle phases at the interface. The three work together to significantly improve the interfacial bonding strength, effectively avoid the problem of reinforcing phase shedding during use, and ensure the stability of the alloy's wear resistance. In this invention, the precisely designed sintering temperature rise curve can prevent premature reaction between WC particles and the matrix, ensure sufficient diffusion between the matrix and the reinforcing phase, and significantly improve the alloy density. This invention achieves a synergistic optimization of high wear resistance and good toughness by rationally controlling the composition of the medium carbon alloy steel matrix and combining it with post-treatment processes such as staged cooling, deep cryogenic treatment and low-temperature tempering. This ensures high hardness while effectively eliminating internal stress, refining the microstructure, and avoiding brittle fracture of the alloy. It also broadens the applicable working conditions of the alloy. Detailed Implementation

[0012] The present invention will be further described below with reference to embodiments. These embodiments are illustrative of the present invention, but the present invention is not limited to these embodiments: Example 1

[0013] A high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy, the iron-based alloy comprising the following components by weight percentage: The composition is as follows: WC 4.5wt%, C 0.4wt%, Cr 1.2wt%, Ni 0.9wt%, Mo 0.3wt%, Si 0.3wt%, Mn 0.5wt%, nano-Al2O3@Co-Y2O3 composite modified particles 0.8wt%, and the remainder is Fe; In WC, fine particles of 1-5μm account for 70wt%, and coarse particles of 5-10μm account for 30wt%. The preparation method of the nano-Al2O3@Co-Y2O3 composite modified particles includes the following steps: S11. Add aluminum isopropoxide to isopropanol at a mass ratio of 5:3, stir and reflux, then add dilute nitric acid at a molar ratio of 1:0.05 to obtain a sol, let it stand for aging, dry it, and grind it to obtain a white powder. S12. Place the white powder in a muffle furnace, heat it to 550℃, and keep it for 3 hours to obtain porous Al2O3 powder; S13. Add porous Al2O3 powder to a mixed solution of cobalt nitrate and yttrium nitrate. The concentration of cobalt nitrate is 0.4 mol / L and the concentration of yttrium nitrate is 0.2 mol / L. The mass-volume ratio of porous Al2O3 powder to the mixed solution is 1 g: 30 mL. After stirring for 2 h, let stand for 15 h, filter and dry, and finally calcine to obtain Al2O3@Co-Y2O3 composite modified particles. Then grind to obtain nano-Al2O3@Co-Y2O3 composite modified particles of 300~800 nm. The above-mentioned method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloys includes the following steps: S1. The metal elements in the weighed iron-based alloy powder are melted and atomized to obtain alloy particles. The alloy particles, C, WC and nano Al2O3@Co-Y2O3 composite modified particles are added to a mixer for mixing to obtain a premix. S2. Add the premix and binder to the mixer at a mass ratio of 100:5. The binder is paraffin wax, polyethylene, polypropylene and stearic acid mixed at a mass ratio of 70:25:10:5 to obtain the mixture. S3. Inject the mixture into the mold for injection molding, then degrease with n-heptane, followed by microwave-assisted thermal degreasing using a stepped heating method: heat from room temperature to 100°C at a rate of 5°C / min, heat to 200°C at a rate of 8°C / min, hold for 0.5h, heat to 300°C at a rate of 8°C / min, hold for 1h, heat to 450°C at a rate of 8°C / min, hold for 1h, and finally heat to 600°C at a rate of 5°C / min, hold for 0.5h. S4. The degreased green billet is sintered by heating from room temperature to 800℃ at a rate of 5℃ / min, from 800℃ to 1200℃ at a rate of 3℃ / min, and from 1200℃ to 1380℃ at a rate of 2℃ / min. After post-treatment, the alloy is cooled in the furnace to 860℃, held for 15 min, and then transferred to a salt bath at 220℃ for staged cooling for 5 min. It is then cooled to -196℃ at a rate of 5℃ / min and held for 3 h for cryogenic treatment. After cryogenic treatment, the furnace temperature is raised to 200℃ and held for 3 h, and then air-cooled to room temperature to obtain a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy.

[0014] Example 2

[0015] A high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy, the iron-based alloy comprising the following components by weight percentage: The composition is as follows: WC 5.5wt%, C 0.5wt%, Cr 1.5wt%, Ni 1.1wt%, Mo 0.45wt%, Si 0.6wt%, Mn 0.8wt%, nano-Al2O3@Co-Y2O3 composite modified particles 1.5wt%, and the remainder is Fe; In WC, 1-5μm fine particles account for 60wt%, and 5-10μm coarse particles account for 40wt%; The preparation method of the nano-Al2O3@Co-Y2O3 composite modified particles includes the following steps: S11. Add aluminum isopropoxide to isopropanol at a mass ratio of 5:3, stir and reflux, then add dilute nitric acid at a molar ratio of 1:0.05 to obtain a sol, let it stand for aging, dry it, and grind it to obtain a white powder. S12. Place the white powder in a muffle furnace, heat it to 600℃, and keep it for 2 hours to obtain porous Al2O3 powder; S13. Add porous Al2O3 powder to a mixed solution of cobalt nitrate and yttrium nitrate. The concentration of cobalt nitrate is 0.8 mol / L and the concentration of yttrium nitrate is 0.3 mol / L. The mass-volume ratio of porous Al2O3 powder to the mixed solution is 1 g: 20 mL. After stirring for 4 h, let stand for 10 h, filter and dry, and finally calcine to obtain Al2O3@Co-Y2O3 composite modified particles. Then grind to obtain nano-Al2O3@Co-Y2O3 composite modified particles of 300~800 nm. The above-mentioned method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloys includes the following steps: S1. The metal elements in the weighed iron-based alloy powder are melted and atomized to obtain alloy particles. The alloy particles, C, WC and nano Al2O3@Co-Y2O3 composite modified particles are added to a mixer for mixing to obtain a premix. S2. Add the premix and binder to the mixer at a mass ratio of 100:9. The binder is paraffin wax, polyethylene, polypropylene and stearic acid mixed at a mass ratio of 60:20:5:2 to obtain the mixture. S3. Inject the mixture into the mold for injection molding, then degrease with n-heptane, followed by microwave-assisted thermal degreasing using a stepped heating method: heat from room temperature to 100°C at a rate of 5°C / min, heat to 200°C at a rate of 8°C / min, hold for 0.5h, heat to 300°C at a rate of 8°C / min, hold for 1h, heat to 450°C at a rate of 8°C / min, hold for 1h, and finally heat to 600°C at a rate of 5°C / min, hold for 0.5h. S4. The degreased green billet is sintered by heating from room temperature to 800℃ at a rate of 5℃ / min, from 800℃ to 1200℃ at a rate of 3℃ / min, and from 1200℃ to 1420℃ at a rate of 2℃ / min. After post-treatment, the alloy is cooled in the furnace to 880℃, held for 10 min, and then transferred to a 200℃ salt bath for staged cooling for 8 min. It is then cooled to -196℃ at a rate of 5℃ / min and held for 2 h for cryogenic treatment. After cryogenic treatment, the furnace temperature is raised to 180℃ and held for 2 h, and then air-cooled to room temperature to obtain a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy.

[0016] Example 3

[0017] A high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy, the iron-based alloy comprising the following components by weight percentage: The composition is as follows: WC 4.8wt%, C 0.42wt%, Cr 1.3wt%, Ni 1wt%, Mo 0.35wt%, Si 0.4wt%, Mn 0.6wt%, nano-Al2O3@Co-Y2O3 composite modified particles 1wt%, and the remainder is Fe; In WC, fine particles of 1-5μm account for 65wt%, and coarse particles of 5-10μm account for 35wt%. The preparation method of the nano-Al2O3@Co-Y2O3 composite modified particles includes the following steps: S11. Add aluminum isopropoxide to isopropanol at a mass ratio of 5:3, stir and reflux, then add dilute nitric acid at a molar ratio of 1:0.05 to obtain a sol, let it stand for aging, dry it, and grind it to obtain a white powder. S12. Place the white powder in a muffle furnace, heat it to 550℃, and keep it for 3 hours to obtain porous Al2O3 powder; S13. Add porous Al2O3 powder to a mixed solution of cobalt nitrate and yttrium nitrate. The concentration of cobalt nitrate is 0.6 mol / L and the concentration of yttrium nitrate is 0.2 mol / L. The mass-volume ratio of porous Al2O3 powder to the mixed solution is 1 g: 26 mL. After stirring for 3 h, let stand for 10 h, filter and dry, and finally calcine to obtain Al2O3@Co-Y2O3 composite modified particles. Then grind to obtain nano-Al2O3@Co-Y2O3 composite modified particles of 300~800 nm. The above-mentioned method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloys includes the following steps: S1. The metal elements in the weighed iron-based alloy powder are melted and atomized to obtain alloy particles. The alloy particles, C, WC and nano Al2O3@Co-Y2O3 composite modified particles are added to a mixer for mixing to obtain a premix. S2. Add the premix and binder to the mixer at a mass ratio of 100:6. The binder is paraffin wax, polyethylene, polypropylene and stearic acid mixed at a mass ratio of 70:22:6:3 to obtain the mixture. S3. Inject the mixture into the mold for injection molding, then degrease with n-heptane, followed by microwave-assisted thermal degreasing using a stepped heating method: heat from room temperature to 100°C at a rate of 5°C / min, heat to 200°C at a rate of 8°C / min, hold for 0.5h, heat to 300°C at a rate of 8°C / min, hold for 1h, heat to 450°C at a rate of 8°C / min, hold for 1h, and finally heat to 600°C at a rate of 5°C / min, hold for 0.5h. S4. The degreased green billet is sintered by heating from room temperature to 800℃ at a rate of 5℃ / min, from 800℃ to 1200℃ at a rate of 3℃ / min, and from 1200℃ to 1400℃ at a rate of 2℃ / min. After post-treatment, the alloy is cooled in the furnace to 880℃, held for 10 min, and then transferred to a salt bath at 220℃ for staged cooling for 5 min. The temperature is then reduced to -196℃ at a rate of 5℃ / min and held for 2 h for cryogenic treatment. After cryogenic treatment, the temperature is heated in the furnace to 200℃ and held for 2 h. Finally, it is air-cooled to room temperature to obtain a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy.

[0018] Example 4

[0019] A high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy, the iron-based alloy comprising the following components by weight percentage: The composition is as follows: WC 5.2wt%, C 0.48wt%, Cr 1.4wt%, Ni 1.1wt%, Mo 0.4wt%, Si 0.5wt%, Mn 0.7wt%, nano-Al2O3@Co-Y2O3 composite modified particles 1.3wt%, and the remainder is Fe; In WC, fine particles of 1-5μm account for 70wt%, and coarse particles of 5-10μm account for 30wt%. The preparation method of the nano-Al2O3@Co-Y2O3 composite modified particles includes the following steps: S11. Add aluminum isopropoxide to isopropanol at a mass ratio of 5:3, stir and reflux, then add dilute nitric acid at a molar ratio of 1:0.05 to obtain a sol, let it stand for aging, dry it, and grind it to obtain a white powder. S12. Place the white powder in a muffle furnace, heat it to 600℃, and keep it for 2 hours to obtain porous Al2O3 powder; S13. Add porous Al2O3 powder to a mixed solution of cobalt nitrate and yttrium nitrate. The concentration of cobalt nitrate is 0.75 mol / L and the concentration of yttrium nitrate is 0.25 mol / L. The mass-volume ratio of porous Al2O3 powder to the mixed solution is 1 g: 22 mL. After stirring for 2.5 h, let stand for 15 h, filter and dry, and finally calcine to obtain Al2O3@Co-Y2O3 composite modified particles. Then grind to obtain nano-Al2O3@Co-Y2O3 composite modified particles of 300~800 nm. The above-mentioned method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloys includes the following steps: S1. The metal elements in the weighed iron-based alloy powder are melted and atomized to obtain alloy particles. The alloy particles, C, WC and nano Al2O3@Co-Y2O3 composite modified particles are added to a mixer for mixing to obtain a premix. S2. Add the premix and binder to the mixer at a mass ratio of 100:8. The binder is paraffin wax, polyethylene, polypropylene and stearic acid mixed at a mass ratio of 65:23:9:3 to obtain the mixture. S3. Inject the mixture into the mold for injection molding, then degrease with n-heptane, followed by microwave-assisted thermal degreasing using a stepped heating method: heat from room temperature to 100°C at a rate of 5°C / min, heat to 200°C at a rate of 8°C / min, hold for 0.5h, heat to 300°C at a rate of 8°C / min, hold for 1h, heat to 450°C at a rate of 8°C / min, hold for 1h, and finally heat to 600°C at a rate of 5°C / min, hold for 0.5h. S4. The degreased green billet is sintered by heating from room temperature to 800℃ at a rate of 5℃ / min, from 800℃ to 1200℃ at a rate of 3℃ / min, and from 1200℃ to 1380℃ at a rate of 2℃ / min. After post-treatment, the alloy is cooled in the furnace to 860℃, held for 15 min, and then transferred to a 200℃ salt bath for staged cooling for 8 min. The temperature is then reduced to -196℃ at a rate of 5℃ / min and held for 3 h for cryogenic treatment. After cryogenic treatment, the temperature is heated in the furnace to 180℃ and held for 3 h, and then air-cooled to room temperature to obtain a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy.

[0020] Example 5

[0021] A high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy, the iron-based alloy comprising the following components by weight percentage: The composition is as follows: WC 5wt%, C 0.45wt%, Cr 1.35wt%, Ni 1wt%, Mo 0.38wt%, Si 0.45wt%, Mn 0.65wt%, nano-Al2O3@Co-Y2O3 composite modified particles 1.2wt%, and the remainder is Fe; In WC, fine particles of 1-5μm account for 65wt%, and coarse particles of 5-10μm account for 35wt%. The preparation method of the nano-Al2O3@Co-Y2O3 composite modified particles includes the following steps: S11. Add aluminum isopropoxide to isopropanol at a mass ratio of 5:3, stir and reflux, then add dilute nitric acid at a molar ratio of 1:0.05 to obtain a sol, let it stand for aging, dry it, and grind it to obtain a white powder. S12. Place the white powder in a muffle furnace, heat it to 580℃, and hold it for 2.5h to obtain porous Al2O3 powder; S13. Add porous Al2O3 powder to a mixed solution of cobalt nitrate and yttrium nitrate. The concentration of cobalt nitrate is 0.75 mol / L and the concentration of yttrium nitrate is 0.25 mol / L. The mass-volume ratio of porous Al2O3 powder to the mixed solution is 1 g: 25 mL. After stirring for 2.5 h, let stand for 14 h, filter and dry, and finally calcine to obtain Al2O3@Co-Y2O3 composite modified particles. Then grind to obtain nano-Al2O3@Co-Y2O3 composite modified particles of 300~800 nm. The above-mentioned method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloys includes the following steps: S1. The metal elements in the weighed iron-based alloy powder are melted and atomized to obtain alloy particles. The alloy particles, C, WC and nano Al2O3@Co-Y2O3 composite modified particles are added to a mixer for mixing to obtain a premix. S2. Add the premix and binder to the mixer at a mass ratio of 100:8. The binder is paraffin wax, polyethylene, polypropylene and stearic acid mixed at a mass ratio of 68:23:8:3.5 to obtain the mixture. S3. Inject the mixture into the mold for injection molding, then degrease with n-heptane, followed by microwave-assisted thermal degreasing using a stepped heating method: heat from room temperature to 100°C at a rate of 5°C / min, heat to 200°C at a rate of 8°C / min, hold for 0.5h, heat to 300°C at a rate of 8°C / min, hold for 1h, heat to 450°C at a rate of 8°C / min, hold for 1h, and finally heat to 600°C at a rate of 5°C / min, hold for 0.5h. S4. The degreased green billet is sintered by heating from room temperature to 800℃ at a rate of 5℃ / min, from 800℃ to 1200℃ at a rate of 3℃ / min, and from 1200℃ to 1400℃ at a rate of 2℃ / min. After post-treatment, the alloy is cooled in the furnace to 870℃, held for 12 min, and then transferred to a salt bath at 220℃ for staged cooling for 6 min. It is then cooled to -196℃ at a rate of 5℃ / min and held for 2.5 h for cryogenic treatment. After cryogenic treatment, the furnace temperature is raised to 200℃ and held for 2 h, and then air-cooled to room temperature to obtain a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy.

[0022] Comparative Example 1 The difference between Comparative Example 1 and Example 5 is that Al2O3@Co-Y2O3 composite modified particles are not added.

[0023] Comparative Example 2 The difference between Comparative Example 2 and Example 5 is that Co and Y2O3 were added directly to the raw materials, with Co being 0.4 wt% and Y2O3 being 0.2 wt%.

[0024] Comparative Example 3 The difference between Comparative Example 3 and Example 5 is that gradient temperature degreasing is not used.

[0025] Comparative Example 4 The difference between Comparative Example 4 and Example 5 is that gradient heating sintering is not used in S4.

[0026] Comparative Example 5 The difference between Comparative Example 5 and Example 5 is that cryogenic treatment and low-temperature tempering are not performed in S4.

[0027] Comparative Example 6 The difference between Comparative Example 6 and Example 5 is that WC uses 5-10μm coarse particles.

[0028] The hardness, density, wear resistance (GB / T12444.1-1990, test force 150N, rotation speed 300rpm, test time 20min) and Charpy impact performance (GB / T229-2007) of the iron-based alloys in Examples 1-5 and Comparative Examples 1-5 of this invention were tested, and the results are shown in Table 1 below.

[0029] Rockwell hardness (HRC) Wear mass (mg) Density Charpy impact at room temperature (J / cm2) Example 1 70.2 15 98 32.6 Example 2 68.5 12 97 30.8 Example 3 71.6 16 98 31.1 Example 4 69.4 15 98 29.7 Example 5 71.0 14 98 30.8 Comparative Example 1 60.6 25 97 26.9 Comparative Example 2 62.3 22 97 28.2 Comparative Example 3 68.2 18 90 25.6 Comparative Example 4 67.9 17 94 27.9 Comparative Example 5 68.7 20 95 28.5 Comparative Example 6 68.6 16 96 29.6 As shown in Table 1, the iron-based alloy prepared by the method of the present invention has high Rockwell hardness and excellent hardness and wear resistance mechanical properties, indicating that the reinforcing phase of the present invention has excellent strengthening effect.

[0030] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy, characterized in that: The iron-based alloy comprises the following components by weight percentage: The composition of the material is as follows: WC 4.5~5.5wt%, C 0.4~0.5wt%, Cr 1.2~1.5wt%, Ni 0.9~1.1wt%, Mo 0.3~0.45wt%, Si 0.3~0.6wt%, Mn 0.5~0.8wt%, nano-Al2O3@Co-Y2O3 composite modified particles 0.8~1.5wt%, and the remainder is Fe; In WC, fine particles of 1-5μm account for 60-70 wt%, and coarse particles of 5-10μm account for 30-40 wt%.

2. The high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy according to claim 1, characterized in that: The preparation method of the nano-Al2O3@Co-Y2O3 composite modified particles includes the following steps: S11. Add aluminum isopropoxide to isopropanol at a mass ratio of 5:3, stir and reflux, then add dilute nitric acid at a molar ratio of 1:0.05 to obtain a sol, let it stand for aging, dry it, and grind it to obtain a white powder. S12. Place the white powder in a muffle furnace, heat it to 550~600℃, and maintain it for 2~3 hours to obtain porous Al2O3 powder; S13. Add porous Al2O3 powder to a mixed solution of cobalt nitrate and yttrium nitrate. The concentration of cobalt nitrate is 0.4~0.8 mol / L, and the concentration of yttrium nitrate is 0.2~0.3 mol / L. The mass-volume ratio of porous Al2O3 powder to the mixed solution is 1 g: 20~30 mL. Stir for 2~4 h, let stand for 10~15 h, filter and dry, and finally calcine to obtain Al2O3@Co-Y2O3 composite modified particles. Then grind to obtain nano-Al2O3@Co-Y2O3 composite modified particles of 300~800 nm.

3. The method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy according to claim 1, characterized in that: Includes the following steps: S1. The metal elements in the weighed iron-based alloy powder are melted and atomized to obtain alloy particles. The alloy particles, C, WC and nano Al2O3@Co-Y2O3 composite modified particles are added to a mixer for mixing to obtain a premix. S2. Add the premix and binder to the mixer. The binder is paraffin wax, polyethylene, polypropylene and stearic acid mixed in a mass ratio of 60~70:20~25:5~10:2~5 to obtain the mixture. S3. Inject the mixture into the mold, perform injection molding, and then degrease with n-heptane. After solvent degreasing, perform microwave-assisted thermal degreasing. S4. The degreased green blank is sintered and post-treated to obtain a high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy.

4. The method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy according to claim 3, characterized in that: The ratio of premix to binder in S2 is 100:5~9.

5. The method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy according to claim 3, characterized in that: The process parameters for microwave-assisted thermal degreasing in S3 are as follows: Stepwise heating degreasing is adopted: the room temperature is increased to 100℃ at a heating rate of 5℃ / min, then increased to 200℃ at a heating rate of 8℃ / min, and held for 0.5h. Then, the temperature is increased to 300℃ at a heating rate of 8℃ / min, and held for 1h. Then, the temperature is increased to 450℃ at a heating rate of 8℃ / min, and held for 1h. Finally, the temperature is increased to 600℃ at a heating rate of 5℃ / min, and held for 0.5h.

6. The method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy according to claim 3, characterized in that: The sintering process parameters in S4 are as follows: heating from room temperature to 800℃ at a rate of 5℃ / min, heating from 800℃ to 1200℃ at a rate of 3℃ / min, and heating from 1200℃ to 1380~1420℃ at a rate of 2℃ / min.

7. The method for preparing high-hardness injection-molded tungsten carbide particle-reinforced iron-based alloy according to claim 3, characterized in that: The post-treatment process in S4 is as follows: the alloy is cooled in the furnace to 860~880℃, held for 10~15min, then transferred to a salt bath at 200~220℃ for graded cooling for 5~8min, cooled to -196℃ at a rate of 5℃ / min, held for 2~3h for cryogenic treatment, and then heated in the furnace to 180~200℃, held for 2~3h, and then air-cooled to room temperature.